I can assure you that humidity will not be a problem for your camera while you are there. In the mean time, you may want to purchase your camera in Kuala Lumpur, as Malaysia do not have any VAT (yet) and cameras are duty free items. About which camera, take a look at the Canon Powershot A570 IS (review). It takes only 2 AA batteries.

Canon Powershot is a good choice, ive been using mine for close to 2 years on my travels, and its still working perfectly fine (except that the shutter doesnt close properly). Its rather hardy, compact, and try to get one that runs on AA batteries which are easy enough to get almost everywhere in the world...